The collapse of vapor bubbles in a spatially non-uniform flow

Pressure gradients act differently on liquid particles and suspended bubble s and are, therefore, capable of inducing a relative motion between the pha ses even when no relative velocity initially exists. As a consequence of th e enhanced heat transfer in the presence of convection, this fact may have a major impact on the evolution of a vapor bubble. The effect is particular ly strong in the case of a collapsing bubble for which, due to the conserva tion of the system's impulse, the induced relative velocity tends to be mag nified when the bubble volume shrinks. A practical application could be, fo r instance, the enhancement of the condensation rate of bubbles downstream of a heated region, thereby reducing the quality of a flowing liquid-vapor mixture. A simple model of the process, in which the bubble is assumed to b e spherical and the flow potential, is developed in the paper. (C) 2000 Els evier Science Ltd. All rights reserved.